1. Field of the Invention
The invention relates generally to solenoids and more particularly to an electrified cylindrical lock having fail safe or fail secure operation using a reversible solenoid having active push or active pull operation.
2. Description of the Prior Art
Cylindrical locks are commonly used for doors. Solenoids have been used for electric control of these locks. Circumstances such as building codes and user preferences dictate whether the locks are required to operate as fail safe (electrically locked) or as fail secure (electrically unlocked). Therefore, to provide full coverage a lock manufacturer must supply the locks in both fail safe and fail secure versions. Of course, this can be accomplished with two different solenoids, one for active push operation and the other for active pull operation. However, this doubles the manufacturer's overhead costs for forecasting, purchasing, inventorying and maintaining two solenoids instead of one. From a user's point-of-view, the two solenoid approach has a disadvantage that he cannot change between fail safe and fail secure without reordering.
There is a need for an electrified cylindrical lock having a single solenoid assembly that can conveniently be reversed to switch over between active push and active pull operation.